QUEBEC CITY, Feb. 22 (UPI) — Canadian scientists say the southern limit of permafrost in the James Bay area is now 80 miles farther north than it was 50 years ago.

University of Laval Professors Simon Thibault and Serge Payette said their research suggests if the trend continues, permafrost — permanently frozen ground — will soon disappear from the region.

The scientists said they measured the retreat of the permafrost border by observing hummocks known as “palsas” that form naturally over ice contained in the soil of northern peat bogs. Conditions in the mounds are conducive to the development of distinct vegetation — lichen, shrubs, and black spruce — making them easy to spot.

In an initial survey in 2004, the researchers examined seven bogs located between the 51st and 53rd parallels. They noted at that time only two bogs contained palsas, whereas aerial photos taken in 1957 showed palsas present in all of the bogs. A second assessment in 2005 revealed the number of palsas present in the two bogs had decreased during the course of one year by 86 percent and 90 percent, in that order.

While climate change is the most probable explanation for the phenomenon, the researchers said a lack of long term climatic data makes it impossible for the researchers to officially confirm the cause.

The study appeared in a recent issue of the journal Permafrost and Periglacial Processes.